The proposed project is primarily a laboratory program designed to validate for mutagenesis studies two plant systems, strains of Tradescantia and Zea and to assess their applicability to in situ carcinogenesis monitoring. The major portion of the proposal involves laboratory testing of 20 known carcinogens plus 5 others to validate the sensitivity of these plant systems to chemical carcinogens. Sensitivity is determined by somatic mutations in Tradescantia and germinal mutations in Zea. In addition, field testing of selected urban industrial sites and a rural control site is proposed to evaluate the applicability of the plants to field testing and the effect of non-carcinogenic environmental factors on the background mutation rate.